The Science Behind Depression

Each year, over 264 million people are affected by depression. Depression is a very serious illness, so naturally, many doctors are trying to find treatments and medicines that will work for their patients.

The majority of patients are often put on antidepressants, but this does not work for every person. This is because depression has a wide variety of causes. For example, if someone's depression is caused by trauma, their treatment might vary from someone who has depression from a genetic factor.

However, depression isn’t simply caused by one chemical. Many different chemicals are involved, causing many people to have similar symptoms.

Additionally, depression can have many various causes. The most common are genetics, trauma, loss, stress, medical problems, chemical imbalances, seasonal changes, and faulty mood regulation within the brain.

Antidepressants work to reduce symptoms, balance neurotransmitters, improve mood, normalize sleep-wake cycles, increase appetite, and improve concentration. However, it is important to remember that these medications only relieve symptoms and might have various side effects.

This is also why many doctors recommend that their patients eat healthy, exercise, and visit a therapist. These treatments are often just as effective as medicine.

In the majority of cases, depression stems from an issue found in brain circuits, nerve connections, and nerve cells. Many researchers believe that antidepressants are able to target these issues, and more specifically, neurotransmitters.

Neurotransmitters are chemical messengers that pass signals from one neuron to another in the brain. These neurotransmitters are composed of chemicals called serotonin, dopamine, and norepinephrine. People with depression have low levels of these chemicals, causing symptoms such as sleep troubles, anxiety, and difficulty concentrating.

Antidepressants that are more commonly prescribed are called reuptake inhibitors.

Reuptake is the reabsorption of neurotransmitters from the synaptic cleft into the nerve cell. Essentially, reuptake allows neurotransmitters to be recycled and reused to send messages within the brain.

Reuptake inhibitors block this reabsorption, forcing the neurotransmitter to remain within the synaptic cleft. This increases the amount of chemical between the synapse and the presynaptic neuron.

Many researchers believe that higher levels of neurotransmitters in the synaptic cleft could help improve communication between nerve cells. It is believed that the increase can strengthen nerve circuits and improve mood.

Another cause of depression is an enlarged and overactive amygdala, caused by high levels of cortisol. The amygdala is a region of the brain associated with emotion and emotional processing. Cortisol is the body’s main stress hormone which controls mood, motivation, and fear.

Cortisol is produced by the adrenal glands and is secreted into the bloodstream. The secretion works by shifting the stressed body to a relaxed state.

Research has indicated that people with depression tend to have higher production levels of cortisol. This is because the body’s natural response to stress is to produce more hormones. The increased amount of cortisol prompts the amygdala to become overactive, causing symptoms such as anxiety and issues with concentration.

When the amygdala is overactive due to stress, it triggers the body’s fight or flight reaction. This often results in an uncontrollable reaction to certain stimuli. The overreacting response to stress is often referred to as “amygdala hijacking”.

In the majority of circumstances, you are able to choose how you wish to respond or react to a situation. You can make these decisions through the frontal lobe within the brain.

However, if you have an overactive amygdala, stressful situations can cause the amygdala to hijack the frontal lobe, and activate the fight or flight response. This is often why people with depression experience symptoms of both depression and anxiety. It is important to remember that not all depression is the same. For each individual, depression has different causes and symptoms.

It is also important to remember that antidepressants are still being researched, and can often take a long time to fully activate and help a patient.

Sources:

- Schimelpfening, Nancy. “What Is the Chemistry Behind Depression?” Verywell Mind, 5 Jan. 2021, www.verywellmind.com/the-chemistry-of-depression-1065137.

- Publishing, Harvard Health. “What Causes Depression?” Harvard Health, www.health.harvard.edu/mind-and-mood/what-causes-depression.

- Bruce, Debra Fulghum. “Causes of Depression.” WebMD, 13 June 2008, www.webmd.com/depression/guide/causes-depression#1.

- “Treatment-Resistant Depression.” Mayo Clinic, 21 July 2017, www.mayoclinic.org/diseases-conditions/depression/in-depth/treatment-resistant-depres sion/art-20044324.

- Melinda. “Depression Treatment - HelpGuide.Org.” HelpGuide, www.helpguide.org/articles/depression/depression-treatment.htm

- “Selective Serotonin Reuptake Inhibitors (SSRIs).” Mayo Clinic, 17 Sept. 2019, www.mayoclinic.org/diseases-conditions/depression/in-depth/ssris/art-20044825.

- Griffin, Morgan. “How Different Antidepressants Work.” WebMD, 5 Nov. 2009, www.webmd.com/depression/how-different-antidepressants-work#1.